You are planning to do things that seem like they would help. Hopefully when you get some more puffers and arrange the plants differently, it will work out better. You sound like you are doing a great job!
I am having the same problem with a juvenile Half banded eel. But even feeding him with a tweezer after putting food in there for the guppies, the guppies love the smell of bloodworms and would come and steal all of his food. I ended up rehoming the majority of my guppies and now I am trying to think of tank mates that will be larger so he won’t swallow them when he gets bigger but who will not put compete him for food. I have been trying to tuck the food into the substrate right in front of him. But he is not quick at gobbling it up as a lot of fish are. Any tank mate ideas to suggest?